A pacemaker electrode intended for releasing a drug is known for example from U.S. Pat. No. 4,922,926.
Implantable pacemaker electrodes have an electrode tip, which must be fixed permanently to the myocardium. In addition to the mechanical anchoring of the electrode tip to the heart muscle, it should be ensured that electrical stimulation pulses can be transmitted under as constant conditions as possible. For this purpose, an electrode device for intracorporal stimulation of the body tissue, known from European patent EP 0 620 024 B1, for example has an electrode head whose surface layer is made of a conducting material, which is partially covered with a layer of high-resistance insulating material. The layer is designed to be so thin that the difference between the distance between the stimulation surface and the heart tissue and between the insulating layer and the heart tissue respectively for an applied electrode device does not result in a threshold effect.
The stimulation threshold of a pacemaker can change over time as a result of tissue fibrosis around the electrode tip. In the extreme case, such a change in the stimulation threshold results in the pacemaker no longer performing its intended function. In cases in which the pacemaker continues to perform its function despite an increase in the stimulation threshold, power consumption increases and hence the service life of the pacemaker battery decreases. For patients this means needing to have frequent checks by the doctor.